Use of botulinum toxin to lateralize true vocal cords: a biochemical method to relieve bilateral abductor vocal cord paralysis.

Using the mongrel dog as an animal model, we studied the effectiveness of botulinum toxin (Oculinum) to lateralize the true vocal cord. This experiment was undertaken in order to determine whether the toxin can improve the airway in subjects with bilateral abductor vocal cord paralysis. The toxin was injected into the cricothyroid muscle to block neuromuscular transmission at the motor end-plate. Paralysis of the cricothyroid muscle was achieved and documented by electromyography and videotaped endoscopy. Paralysis of the cricothyroid muscle decreases the tension of the true vocal cord and allows the cord to take a more lateral position. In this preliminary report, the literature is reviewed, the effect of and action of the toxin are discussed, and the results of the experimental protocol, establishment of dose-response curves, and techniques of injection are presented. Preliminary data suggest that there is an increase in the airway by lateralizing the true vocal cord with this biologic substance, and that this method may have many applications in clinical medicine for the otolaryngologist-head and neck surgeon.